driver core: Add fw_devlink_parse_fwtree()

This function is a wrapper around fwnode_operations.add_links().

This function parses each node in a fwnode tree and create fwnode links
for each of those nodes. The information for creating the fwnode links
(the supplier and consumer fwnode) is obtained by parsing the properties
in each of the fwnodes.

This function also ensures that no fwnode is parsed more than once by
marking the fwnodes as parsed.

Signed-off-by: Saravana Kannan <saravanak@google.com>
Link: https://lore.kernel.org/r/20201121020232.908850-13-saravanak@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/base/core.c

@@ -1542,6 +1542,25 @@ static bool fw_devlink_is_permissive(void)
 	return fw_devlink_flags == DL_FLAG_SYNC_STATE_ONLY;
 }
 
+static void fw_devlink_parse_fwnode(struct fwnode_handle *fwnode)
+{
+	if (fwnode->flags & FWNODE_FLAG_LINKS_ADDED)
+		return;
+
+	fwnode_call_int_op(fwnode, add_links, NULL);
+	fwnode->flags |= FWNODE_FLAG_LINKS_ADDED;
+}
+
+static void fw_devlink_parse_fwtree(struct fwnode_handle *fwnode)
+{
+	struct fwnode_handle *child = NULL;
+
+	fw_devlink_parse_fwnode(fwnode);
+
+	while ((child = fwnode_get_next_available_child_node(fwnode, child)))
+		fw_devlink_parse_fwtree(child);
+}
+
 static void fw_devlink_link_device(struct device *dev)
 {
 	int fw_ret;

include/linux/fwnode.h

@@ -15,12 +15,20 @@
 struct fwnode_operations;
 struct device;
 
+/*
+ * fwnode link flags
+ *
+ * LINKS_ADDED: The fwnode has already be parsed to add fwnode links.
+ */
+#define FWNODE_FLAG_LINKS_ADDED		BIT(0)
+
 struct fwnode_handle {
 	struct fwnode_handle *secondary;
 	const struct fwnode_operations *ops;
 	struct device *dev;
 	struct list_head suppliers;
 	struct list_head consumers;
+	u8 flags;
 };
 
 struct fwnode_link {